【作者】 徐强；

【导师】 董威；

【作者基本信息】 西安工业大学 ， 精密仪器及机械， 2010， 硕士

【摘要】 磁化电源是软磁材料直流磁特性测量系统中的重要组成部分,传统的磁化电源均采用线性电源。随着电源技术的发展,目前,在很多领域开关电源以其重量轻、体积小、效率高、功耗低等优点迅速取代了线性电源成为大多数电子设备的供能电源。但是,相对线性电源,开关电源有个明显的缺点就是输出纹波电压大。如果采用开关电源做磁化电源,该缺点必定会影响测量结果,造成测量误差。本文以国家标准GB3657-83软磁材料直流磁特性测量方法为平台,首先,通过对软磁材料磁化过程的研究以及相关实验,分析了纹波对直流磁特性测量的影响。其次,针对开关电源输入级整流过程,分析了低频纹波的产生,并根据开关电源宏模型,采用功率匹配法和等效电流源法推导了开关电源低频纹波电压的计算公式；针对反激式变换器的能量传输过程,分析了开关频率纹波的产生机理,并根据反激变换器的电感完全供能模式(CISM),不完全电感供能且连续电流模式(ⅡSM-CCM),不完全电感供能且断续电流模式(ⅡSM-DCM)三种工作模式,进行了相应的纹波计算；针对开关电源纹波电压的测量,介绍了几种业界认可的示波器测量法。然后,又针对反激式开关电源的低频纹波和开关频率纹波,设计了相应的纹波衰减电路,包括LC谐振滤波器和LDO电路,并进行了Pspice仿真,仿真结果表明,纹波衰减效果明显。最后,根据软磁材料直流磁特性测量系统中需要恒定的磁化电流来提供恒定磁化场的特点,从稳流的角度来消除开关电源纹波对直流磁特性测量的影响,设计了适合提供恒定磁化电流的恒流磁化电源。实验表明,应用纹波衰减后的开关电源,测量磁感应强度的相对误差小于±3%,符合国标规定。本文的研究工作为开关电源在磁特性测量中的应用提供了一定的参考价值。更多还原

【Abstract】 The linear power supply is traditionally used as magnetization power supply which is an important device in measuring DC magnetic properties of soft magnetic material. Nowadays, it shows a strong need in application if the traditional linear power supply could be replaced by switching power supplies. With the unique properties such as low power consumption, small in size and light in weight, portable and high efficiency SMPS (switching power supply) will be used in many application fields and become the main stream in engineering. However, the ripple voltage in output of SMPS restricts its application. In the measurement of magnetic properties of materials this disadvantage will definitely affect the measurement results and result in measurement error.GB3657-83 is the national standard measurement methods of DC magnetic properties of soft magnetic materials. First of all, according to research and experiments related magnetization process of soft magnetic materials, the influence of ripple voltage in DC magnetic properties of measurement is analyzed. Secondly, the ripple voltage output in low-frequency during rectification process in SMPS is analyzed. Formulations for ripple voltage output in low-frequency are deduced by power matching method and equivalent current source circuit method. During the energy transmission process, switching frequency ripple voltage of fly-back converter is analyzed. The converter is divided into three operating phrases, i.e., the complete inductor supply mode (CISM), the incomplete inductor supply mode with continuous conduction mode (IISM-CCM), and the incomplete inductor supply mode with discontinuous conduction mode (IISM-DCM). Formulations for switching frequency ripple voltage are deduced respectively in each mode. The measuring ripple voltage can be obtained by using oscilloscope method. Than, the ripple voltage attenuation circuits are designed for ripple voltage of low-switching frequency including the LC resonant filters and LDO circuits. The Simulation with Pspice indicates that ripple voltage is obviously attenuation. Finally, in DC magnetic properties measurement system of the soft magnetic material, a constant current source is designed to eliminate the ripple voltage in the magnetization current.Experimental results show that there is no any difference between the application of adjusted switching power supply in DC magnetic properties measurement system and GB3657-83.Relative error of the measuring result is less than±3%.The textual research work can provide important reference value for the application of switching power supply in magnetic properties measurement system.更多还原